Exchange interaction parameters and adiabatic spin-wave spectra of ferromagnets: A "renormalized magnetic force theorem"

TL;DR

This paper introduces a renormalized magnetic force theorem that corrects systematic errors in calculating exchange interactions and spin-wave spectra of ferromagnets, significantly improving agreement with experimental Curie temperatures.

Contribution

It presents a new renormalization method for the magnetic force theorem that reduces errors without increasing computational complexity.

Findings

Improved accuracy of spin-wave spectra calculations.

Better agreement with experimental Curie temperatures for Fe and Ni.

Simple renormalization applicable to systems with one atom per unit cell.

Abstract

The ``magnetic force theorem'' is frequently used to compute exchange interaction parameters and adiabatic spin-wave spectra of ferromagnets. The interest of this approach is that it allows to obtain these results from a non-self-consistent calculation of the (single-electron) band energy only, which greatly reduces the computational effort. However, as discussed by various authors, this approach entail some systematic error. Here, a ``renormalized magnetic force theorem'' allowing to remove this systematic error without increasing significantly the computational effort is presented. For systems with one atom per unit cell, it amounts to a simple renormalization of the spin-wave spectrum. This renormalization greatly improves the agreement between calculated and experimental Curie temperatures of Fe and Ni.